BSLM-06 PROGNOSTIC SIGNIFICANCE OF CEREBROSPINAL FLUID GLUCOSE AND PROTEIN LEVELS IN METASTATIC BREAST CANCER PATIENTS WITH LEPTOMENINGEAL DISEASE: A RETROSPECTIVE STUDY

The prognostic significance of cerebrospinal fluid (CSF) glucose and protein levels among patients with leptomeningeal disease (LMD) is unknown. This single-institution retrospective study aims to investigate the association of CSF glucose and protein levels with overall survival (OS) among metastatic breast cancer (MBC) patients with LMD.

MBC patients diagnosed with LMD between Jan 1st, 2010, and Jan 1st, 2023, were included. Patients without known CSF glucose or protein levels at the time of LMD diagnosis were excluded. OS was evaluated using the Kaplan-Meier method and compared using the log-rank test. For multivariate analysis, a step-wise model selection was performed after the inclusion of sub-type of interest, and variables meeting entry (p<0.10) and staying criteria (p<0.05). Median glucose and protein levels were compared using the Wilcoxon rank-sum test.

28 patients met inclusion criteria. Positive CSF cytology samples (CSF+) had significantly lower glucose levels vs CSF cytology negative samples (CSF-) [median (IQR) 40 (18-58) vs. 64 (53-92) mg/dl, p=0.006]. Prior study from this data set had shown that the CSF- group was associated with better OS vs the CSF+ group. Hence, four groups were created based on the CSF (+/-) and glucose (Low vs High/Normal). Median OS (months), 95% confidence Interval (CI) for CSF+/Glucose_Low, CSF+/Glucose_Normal/High, CSF-/Glucose_Low and CSF-/Glucose_High/Normal were 3.4(0.23-NE), 16.5(2.9-NE), 3.1(1.28-NE), 51.5(4.9-NE), p=0.03. Glucose_Low overall was associated with shorter OS in multivariate analysis [hazard ratio (HR), 95%CI 4.64 (1.71, 13.2)]. Median CSF protein was not different between CSF+/– groups. Median OS (months), 95%CI for Protein_High and Protein_Low /Normal groups were 28.5 (2.9, 51.5) vs. 6.5 (0.85, 8.0), p=0.36. In multivariate analysis, CSF protein level was not associated with OS.

The association between low CSF glucose level and worse survival among patients with MBC LMD was observed.